Optical and electrochemical properties of polyfluorenes with pyridine-triphenylamine bipolar unit

Two new polyfluorenes were synthesized by Suzuki coupling polymerization, and their photophysical and electrochemical properties were studied. Both polymers contained the bipolar unit 4-(2,6-diphenylpyridin-4-yl)phenyl-diphenylamine consisting of pyridine (Py) and triphenylamine (TPA) subunits. The bipolar unit was linked to the polymer chain via TPA or Py subunit, which affected the properties of the polymers. The polymers showed a weak intramolecular charge transfer character. They showed emission at 466 nm in solution and at 512-538 nm in thin film. Their emission could be tuned by protonation and N-alkylation of Py. Cyclic voltammetry experiments showed a quasi-reversible oxidation process for both polymers. Their highest occupied molecular orbital levels were estimated at - 5.13 and - 5.21 eV.